The present invention relates generally to virtual private networks and, more particularly, to calculating the cost of providing service over circuit-based virtual private networks.
Determining the cost of the operation of a communications network is an important aspect of determining the appropriate amount to charge customers for services provided over the network. In digital telephony networks where the network is implemented at the physical layer, for example, the operating cost of the network is relatively easy to determine. Specifically, the total cost of operating such a network can generally be calculated as the sum of the cost of the hardware (e.g., switches, routers, or multiplexers) and the cost of providing bandwidth for the links between nodes in the network. More particularly, the cost of the hardware in such a calculation is a combination of the depreciated value of the hardware purchase price and the hardware maintenance charges. The cost attributed to the links depends on whether the network operator leases or owns the transmission lines, such as trunk lines. If the network operator leases the lines, for example, the cost of the links is the sum of the monthly lease rate for the lines. If the network operator owns the lines, the cost of the link is the depreciated purchase price of the lines.
While determining the cost of a network having dedicated physical resources is relatively simple, calculating the cost of other networks is not as easy. For example, Virtual Private Networks (VPNs) have grown in popularity as a method of providing relatively secure communication between the nodes in a network. As is well-known to one skilled in the art, a virtual private network does not typically have dedicated network hardware but, instead, is a secure virtual network created across a public network, such as the Internet, by establishing one or more defined private links using, for example, encryption and tunneling techniques. As such, a VPN shares resources, such as the equipment facilities of a public network, with other virtual private networks as well as other non-VPN traffic. As is well known, VPNs maintain privacy by encapsulating messages in packets or frame relay frames to separate the messages from those of other VPNs that share the same public network. Encryption and tunneling function to ensure the privacy of messages transmitted across a VPN. Therefore, such networks are very advantageous in many regards. However, due to the foregoing sharing of the network resources, calculating the cost attributed to service provided to each user is difficult.